This project brings a developmental approach to the education of poor children in order to understand why they start off elementary school behind their peers and then fall further behind from year to year. With data from a large sample of American children in the NICHD Study of Early Child Care and Youth Development (SECCYD), growth curve modeling techniques will estimate trajectories of math and reading achievement from the beginning of elementary school up to fifth grade for poor, near-poor, and non-poor children, assess the degree to which economic differences in these trajectories are a function of corresponding differences in psychological development, social competence, and family processes leading up to the transition into elementary school, evaluate the degree to which these disparities in achievement occur and how the developmental correlates of achievement vary across race/ethnic populations and school types, and explore the degree to which exposure to high-quality programs and classroom environments condition these economic disparities. Such research will inform social policy by identifying critical intervention points and manipulable risk and protective factors that can be addressed or leveraged in such intervention. Relevance to Public Health Health disparities, including those related to economic status, are a major public health issue in the U.S. This project will identify specific mechanisms that reproduce these disparities across generations by investigating how aspects of poor children's psychosocial development and family processes disrupt their transitions into formal schooling. Because this transition point is the foundation of the educational career and because educational attainment is the foundation of health and mortality in the long term, this project will directly inform the search for policy levers in efforts to combat health disparities.